JP2010174335A - Method for evaluating low-temperature reduction disintegration of sintered ore - Google Patents
Method for evaluating low-temperature reduction disintegration of sintered ore Download PDFInfo
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- 230000009467 reduction Effects 0.000 title claims abstract description 127
- 238000000034 method Methods 0.000 title claims abstract description 20
- 238000012360 testing method Methods 0.000 claims abstract description 68
- 230000008859 change Effects 0.000 claims abstract description 9
- 238000002156 mixing Methods 0.000 claims abstract description 5
- 239000002994 raw material Substances 0.000 claims abstract description 4
- 238000000227 grinding Methods 0.000 claims description 36
- 238000010298 pulverizing process Methods 0.000 claims description 22
- 238000011156 evaluation Methods 0.000 claims description 21
- 239000000843 powder Substances 0.000 claims description 16
- 238000004321 preservation Methods 0.000 claims description 14
- 238000007796 conventional method Methods 0.000 abstract 1
- 238000006722 reduction reaction Methods 0.000 description 119
- 239000007789 gas Substances 0.000 description 33
- 239000000203 mixture Substances 0.000 description 15
- LIKBJVNGSGBSGK-UHFFFAOYSA-N iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Fe+3].[Fe+3] LIKBJVNGSGBSGK-UHFFFAOYSA-N 0.000 description 11
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 10
- 229910052595 hematite Inorganic materials 0.000 description 10
- 239000011019 hematite Substances 0.000 description 10
- 230000000694 effects Effects 0.000 description 7
- 238000002474 experimental method Methods 0.000 description 6
- 229910052742 iron Inorganic materials 0.000 description 5
- 239000003638 chemical reducing agent Substances 0.000 description 4
- 238000009423 ventilation Methods 0.000 description 4
- 238000005259 measurement Methods 0.000 description 3
- 238000007873 sieving Methods 0.000 description 3
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
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- 238000006731 degradation reaction Methods 0.000 description 2
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- 238000005338 heat storage Methods 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 1
- 229910000805 Pig iron Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 230000003292 diminished effect Effects 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
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- 230000035699 permeability Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
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Abstract
Description
本発明は、鉱石系原料である焼結鉱の高炉内における低温還元粉化の評価方法に関するものである。 The present invention relates to a method for evaluating low-temperature reduced pulverization of sintered ore, which is an ore-based material, in a blast furnace.
鉄鉱石から銑鉄を取り出すための炉である高炉の安定操業において、シャフト部の通気確保はたいへん重要である。しかし、シャフト上部において、焼結鉱が低温還元粉化した場合、発生した粉がシャフト上部の通気を阻害する。
また、低温還元粉化した粉が高炉上部から高炉内熱保存帯入り口にかけて蓄積すると、シャフト部全体の通気が悪化する。その結果、吹き抜けなどの大きなトラブルが発生したり、シャフト下部のガス流れが偏流化したりして、シャフト効率が低下する、といった弊害があった。そのため、従来より、焼結鉱の低温還元粉化を管理する指標として、JIS-RDI試験（JIS M 8720：2001年、以下年は省略する）が使用されている。
In the stable operation of a blast furnace, which is a furnace for extracting pig iron from iron ore, it is very important to ensure the ventilation of the shaft section. However, when the sintered ore is reduced to a low temperature powder at the upper part of the shaft, the generated powder inhibits the ventilation of the upper part of the shaft.
Moreover, if the powder reduced to low temperature is accumulated from the upper part of the blast furnace to the entrance of the heat preservation zone in the blast furnace, the ventilation of the entire shaft part deteriorates. As a result, there are problems such as occurrence of a large trouble such as blow-through, or a deviation in the gas flow at the lower portion of the shaft, resulting in a reduction in shaft efficiency. Therefore, the JIS-RDI test (JIS M 8720: 2001, the following years are omitted) has been used as an index for managing low-temperature reduced powdering of sintered ore.
上述したJIS-RDI試験の還元条件は、焼結鉱粒径：16〜19mm、焼結鉱重量：500g、還元温度：550℃、還元時間：30分、還元ガス組成は、CO:CO2:N2＝30：０：70であり、CO：CO2に注目すれば、100：０である。その後、ドラム試験と呼ばれる所定径の筒による回転粉化が行われ、ついで篩分を行い、2.8mm角の網を通過したもの（以下-2.8mmとする）の割合を測定し、その値がJIS-RDI値となる。 The reduction conditions of the JIS-RDI test described above are as follows: sintered ore particle size: 16 to 19 mm, sintered ore weight: 500 g, reduction temperature: 550 ° C., reduction time: 30 minutes, reducing gas composition is CO: CO 2 : N 2 = 30: 0: 70, and focusing on CO: CO 2 , it is 100: 0. After that, rotating powdering with a cylinder of a predetermined diameter called a drum test was performed, followed by sieving and measuring the ratio of what passed through a 2.8mm square net (hereinafter referred to as -2.8mm), and the value was JIS-RDI value.
ここで、JIS-RDI試験条件と高炉内温度・ガス測定結果を図１に示す。図中、●印の位置がJIS-RDIの温度および雰囲気である。
一方、(1)BF(RAR:445)は、還元剤比445kg/t・時の高炉内ガス組成、(2)BF(RAR:452)は、還元剤比452kg/t・時の高炉内ガス組成、(3)BF(RAR:486)は、還元剤比486kg/t・時の高炉内ガス組成、を表していて、いずれも雰囲気中にCO2が含まれている。同図から明らかなように、JIS-RDI試験のガス組成は、550℃における高炉内ガス組成と大きく異なっている。そのため、このJIS-RDI値では、正確に高炉内、とりわけ、高炉内熱保存帯入り口における低温還元粉化の量を評価することは難しいと考えられる。
Here, JIS-RDI test conditions and blast furnace temperature / gas measurement results are shown in FIG. In the figure, the position marked with ● is the JIS-RDI temperature and atmosphere.
On the other hand, (1) BF (RAR: 445) is the gas composition in the blast furnace at a reducing agent ratio of 445 kg / t · h, and (2) BF (RAR: 452) is the gas in the blast furnace at a reducing agent ratio of 452 kg / t · h. The composition, (3) BF (RAR: 486), represents the gas composition in the blast furnace with a reducing agent ratio of 486 kg / t · h, both of which contain CO 2 in the atmosphere. As is clear from the figure, the gas composition of the JIS-RDI test is significantly different from the gas composition in the blast furnace at 550 ° C. Therefore, with this JIS-RDI value, it is considered difficult to accurately evaluate the amount of low-temperature reduced powdering in the blast furnace, especially in the blast furnace thermal preservation zone entrance.
そこで、特許文献１および２には、高炉操業計画や原料鉄鉱石の性状の変動に対応し、各々の変動に応じたJIS-RDI上限管理値の決定方法が提案されている。同じく、特許文献３には、高炉内の所定位置における温度およびガス組成を測定し、この温度およびガス組成の測定結果に基づいて高炉中のヘマタイトの減少量を求め、高炉内における焼結鉱の還元粉化量を推定する方法が提案されている。さらに、特許文献４には、微粉炭吹込み高炉操業条件下における焼結鉱の還元粉化温度域での滞留時間および雰囲気ガスの還元ポテンシャルを正確に評価することで、まず、還元試験条件を設定し、その条件を用いて低SiO2焼結鉱の還元粉化性を評価するという方法が示されている。 Therefore, Patent Documents 1 and 2 propose a method for determining a JIS-RDI upper limit management value corresponding to each change in response to changes in the properties of the blast furnace operation plan and raw iron ore. Similarly, in Patent Document 3, the temperature and gas composition at a predetermined position in the blast furnace are measured, and the amount of hematite in the blast furnace is determined based on the measurement results of the temperature and gas composition. A method for estimating the amount of reduced powder is proposed. Furthermore, in Patent Document 4, by accurately evaluating the residence time in the reduced pulverization temperature range of the sintered ore and the reduction potential of the atmospheric gas under the pulverized coal injection blast furnace operating conditions, He sets, the method is shown of evaluating reduction degradation of the low SiO 2 sinter with the condition.
しかし、特許文献１および２では、焼結鉱銘柄による還元粉化量の差を検出することが非常に煩雑でかつ困難という問題があった。 However, Patent Documents 1 and 2 have a problem that it is very complicated and difficult to detect the difference in the amount of reduced powder due to the sintered ore brand.
また、特許文献３の高炉内の所定位置の温度およびガス組成に基づいて、ヘマタイト減少量を求める方法については、ある焼結鉱種における、各位置の実際の還元粉化量の大小は検出できるが、別の焼結鉱種による還元粉化量の差は推定できないという問題があった。
さらに、特許文献４の微粉炭吹込み高炉操業条件下における焼結鉱の還元粉化温度域での滞留時間および雰囲気ガスの還元ポテンシャルを正確に評価して還元条件を設定する方法は、その対象が低SiO2含有焼結鉱であり、高炉の操業条件もパラメータとして影響するため、結果として操業条件ごとの試験が必要となるという問題があった。
つまり、特許文献３および４に示された発明においては、各々の還元試験条件を、個別に設定しなければならず、高炉による連続製造時等では、適切なタイミングで、評価結果を反映させることができないという問題があった。
Moreover, about the method of calculating | requiring the amount of hematite reduction | decrease based on the temperature and gas composition of the predetermined position in the blast furnace of patent document 3, the magnitude of the actual reduction | restoration powder amount of each position in a certain sintered ore type | mold can be detected. However, there is a problem that the difference in the amount of reduced powder by different sintered ore types cannot be estimated.
Further, the method of accurately evaluating the residence time in the reduced pulverization temperature range of sintered ore and the reduction potential of the atmospheric gas under the pulverized coal injection blast furnace operating conditions of Patent Document 4 Is a low SiO 2 containing sinter, and the operating conditions of the blast furnace are also affected as parameters, and as a result, there is a problem that a test for each operating condition is required.
In other words, in the inventions disclosed in Patent Documents 3 and 4, each reduction test condition must be set individually, and the evaluation results should be reflected at an appropriate timing during continuous production using a blast furnace. There was a problem that could not.
本発明は、上述した現状に鑑み、従来のJIS評価方法では困難であった焼結鉱銘柄の違いによる粉化率の差を検出可能とし、さらに、操業に応じた試験条件の変更を行う必要のない統一還元試験条件を用いて、高炉内における焼結鉱の還元粉化量、特に、従来、精度良く評価することが難しいとされた熱保存帯入り口における焼結鉱の還元粉化量をも、正確に評価することができる焼結鉱の低温還元粉化評価方法を提供することを目的とする。 The present invention makes it possible to detect the difference in the pulverization rate due to the difference in sintered ore brands, which has been difficult with the conventional JIS evaluation method in view of the above-described current situation, and further, it is necessary to change the test conditions according to the operation. The reduction powdered amount of sintered ore in the blast furnace, especially the reduced powdered amount of sintered ore at the entrance of the heat preservation zone, where it was difficult to evaluate with high accuracy, was used. It is another object of the present invention to provide a method for evaluating low-temperature reduction powdering of sintered ore that can be accurately evaluated.
以下、本発明の解明経緯について説明する。
発明者らは、まず、JIS-RDI試験における還元試験の雰囲気がCOガスのみの還元であることに注目（図１参照）し、高炉内における環境に沿ったCO2を混合させて還元試験を行い、還元ガスが低温還元粉化におよぼす影響をCOガスのみの場合と比較した。この際、JIS-RDI値の異なる3種類の焼結鉱を用い、還元率が低温還元粉化に及ぼす影響も同時に確認している。図２に、この調査に用いた還元装置を示す。図中、１ははかり（balance）、２はエアシリンダ（Air Cylinder）、３はロードセル（Load cell）、４は排気ガス分析（Exhaust gas analysis）、５は熱電対（Thermocouple）、６は試料（Sample）、７はアルミナボール（Alumina ball）、８は電気ヒータ（Electric heater）である。
The elucidation process of the present invention will be described below.
The inventors first noticed that the atmosphere of the reduction test in the JIS-RDI test is the reduction of only CO gas (see Fig. 1), and mixed the CO 2 along the environment in the blast furnace to perform the reduction test. The effect of reducing gas on low-temperature reduced powdering was compared with that of CO gas alone. At this time, three types of sintered ore with different JIS-RDI values were used, and the effect of the reduction rate on low-temperature reduced powdering was also confirmed at the same time. FIG. 2 shows the reduction device used for this investigation. In the figure, 1 is a balance, 2 is an air cylinder, 3 is a load cell, 4 is an exhaust gas analysis, 5 is a thermocouple, 6 is a sample ( Sample, 7 is an alumina ball, and 8 is an electric heater.
図３の「experiment」の欄にJIS-RDI試験条件と比較した本試験条件を示す。同図に示したとおり、還元管の径(Reduction tube diameter)、試料サイズ(Sample size)、試料質量(Sample mass)および還元温度(Reduction temperature)は、JIS-RDI試験条件に準拠した。また、雰囲気(Reduction gas composition)は、vol％でCO／N2＝30/70およびCO／CO2／N2＝22.5/22.5/55とし、時間(Reduction time)を15,30,39,57および90分の5水準とした。さらに、図４に本試験に用いた原料(sample)の性状を示す。 The “experiment” column in FIG. 3 shows the test conditions compared with the JIS-RDI test conditions. As shown in the figure, the reduction tube diameter, the sample size, the sample mass, and the reduction temperature were in accordance with JIS-RDI test conditions. The atmosphere (Reduction gas composition) is CO / N 2 = 30/70 and CO / CO 2 / N 2 = 22.5 / 22.5 / 55 in vol%, and the reduction time is 15, 30, 39, 57 And 5/90 levels. Further, FIG. 4 shows the properties of the raw material (sample) used in this test.
ついで、JIS-RDI試験条件に準じて、ドラムテストおよび篩分テストを行った。上記のCO2混合条件で得られた-2.8mm分率をRDI´値とする。
図５に還元率とRDI値およびRDI´値との関係を示す。
Next, a drum test and a sieving test were performed according to the JIS-RDI test conditions. The −2.8 mm fraction obtained under the above CO 2 mixing conditions is defined as the RDI ′ value.
FIG. 5 shows the relationship between the reduction rate, the RDI value, and the RDI ′ value.
同図に示したとおり、同じ還元率でもCO＋CO2還元の方がCO還元よりも還元粉化が促進されることが分かった。
そこで、還元後の焼結鉱を断面観察し、還元ガスが還元挙動に及ぼす影響について調査を行った。ここで、上記にて実施した試験条件は、ヘマタイトがマグネタイトに還元される領域である。また、ヘマタイトは、焼結鉱の組織中に出現する鉱物のうちで最も明るいため、ヘマタイトのみを撮像できるという特性がある。これを利用して、画像処理を行い、ヘマタイト組織を鮮明化して、ヘマタイトの存在位置を特定し、還元挙動を観察した。図６にCO還元後（還元率5.0％）およびCO＋CO2還元後（還元率2.0％）の焼結鉱の断面組織中ヘマタイトを鮮明化した写真を示す。CO還元後の断面組織中ヘマタイトは、中心部に存在している。このことから、この還元反応は、局所的にトポケミカルに進行したものと考えられる。一方、CO＋CO2還元後の断面組織中ヘマタイトは、全体的に分散して存在している。このことから、この還元反応は、広域的に均一反応して進行したものと考えられる。
As shown in the figure, it was found that CO + CO 2 reduction promotes reduced powdering more than CO reduction even at the same reduction rate.
Then, the cross section of the sintered ore after reduction was observed, and the effect of reducing gas on the reduction behavior was investigated. Here, the test conditions implemented above are regions where hematite is reduced to magnetite. Moreover, hematite has the property that only hematite can be imaged because it is the brightest of the minerals that appear in the structure of sintered ore. Using this, image processing was performed, the hematite structure was clarified, the location of hematite was specified, and the reduction behavior was observed. FIG. 6 shows photographs in which the hematite in the cross-sectional structure of the sintered ore after CO reduction (reduction rate 5.0%) and CO + CO 2 reduction (reduction rate 2.0%) is clarified. Hematite in the cross-sectional structure after CO reduction exists in the center. From this, it is considered that this reduction reaction locally progressed to topochemical. On the other hand, the hematite in the cross-sectional structure after CO + CO 2 reduction is dispersed throughout. From this, it is considered that this reduction reaction proceeded with uniform reaction over a wide area.
以上の観察結果より、焼結鉱は、還元された周辺部にクラックが発生して粉化現象が生じると考えると、CO還元の場合は、局所的な還元しかなされず、CO＋CO2還元の場合は、広域的に還元反応が生じているために、CO還元に比べて粉化が促進されるものと考えられる。
この還元範囲の差は、CO還元とCO＋CO2還元との還元反応の挙動が異なることを示唆しており、粉化の挙動が異なることにもつながっている。従って、高炉内の還元粉化を正しく評価するためには、高炉内条件に沿ったCO＋CO2還元で行った方が有利であることが分かる。
From the above observation results, considering that sinter ore is cracked in the reduced peripheral area and causes a pulverization phenomenon, in the case of CO reduction, only local reduction is achieved, and in the case of CO + CO 2 reduction It is considered that pulverization is promoted compared with CO reduction because of the reduction reaction occurring in a wide area.
This difference in the reduction range suggests that the behavior of the reduction reaction between CO reduction and CO + CO 2 reduction is different, and also leads to the difference in the behavior of powdering. Therefore, it can be seen that in order to correctly evaluate the reduction pulverization in the blast furnace, it is more advantageous to perform the CO + CO 2 reduction in accordance with the blast furnace conditions.
次に、従来、とりわけ推定が難しいとされた高炉内熱保存帯入り口における焼結鉱の還元粉化挙動を調査するために、還元試験時のガス組成を、還元試験時の温度域ごとにガス組成を設定して行った。この設定は、高炉内の履歴を模擬するもので、図７に試験条件を示す。図８に実験試料の性状を示す。 Next, in order to investigate the reduction powdering behavior of sintered ore at the entrance of the blast furnace thermal preservation zone, which has been considered to be difficult to estimate, the gas composition during the reduction test is determined according to the temperature range during the reduction test. The composition was set. This setting simulates the history in the blast furnace, and the test conditions are shown in FIG. FIG. 8 shows the properties of the experimental sample.
到達還元温度は、JIS-RDI試験条件である550℃、一般的に還元粉化が終了すると考えられている700℃、および高炉の熱保存帯入口温度に相当する1000℃の３条件で行った。
ここで、低温還元粉化が起こる温度域の滞留時間が長くなるほど、低温還元粉化が促進されると言われており、本実験では、低温還元粉化が起こる温度域の500〜550℃の滞留時間を変更して、この滞留時間が還元粉化に及ぼす影響を調査した。図９に1000℃まで還元を行った場合の500〜550℃の滞留時間とRDI´の関係を示す。500〜550℃の滞留時間が10分までは滞留時間の増加とともに還元粉化が進行するが、滞留時間が10分以上になると還元粉化は一定となることが分かった。
The ultimate reduction temperature was three conditions: 550 ° C, which is the JIS-RDI test condition, 700 ° C, which is generally considered to finish reducing powdering, and 1000 ° C, which corresponds to the inlet temperature of the heat storage zone of the blast furnace. .
Here, it is said that the longer the residence time in the temperature range where low temperature reduced powdering occurs, the lower the temperature reduced powdering is promoted. In this experiment, the temperature range of 500 to 550 ° C. where low temperature reduced powdering occurs. The residence time was changed, and the effect of this residence time on reduced powdering was investigated. FIG. 9 shows the relationship between the residence time of 500 to 550 ° C. and RDI ′ when the reduction is performed to 1000 ° C. It was found that the reduction powdering progressed with the increase of the residence time until the residence time at 500 to 550 ° C. was 10 minutes, but the reduction powdering became constant when the residence time was 10 minutes or more.
上述した滞留時間と還元剤比（RAR）を考えると、500〜550℃の滞留時間10分は、RAR＝465kg/tに相当する。従って、高炉の操業条件で、RAR＞465kg/tの場合、RARは465kg/tまで低下すると共に還元粉化が促進されるが、RAR＜465kg/tでは、RARの変化が生じないため、還元粉化量は一定になると推定される。 Considering the residence time and reducing agent ratio (RAR) described above, a residence time of 10 minutes at 500 to 550 ° C. corresponds to RAR = 465 kg / t. Therefore, under the operating conditions of the blast furnace, when RAR> 465 kg / t, RAR is reduced to 465 kg / t and reduced powdering is promoted. However, when RAR <465 kg / t, there is no change in RAR. It is estimated that the amount of pulverization becomes constant.
つまり、高炉内熱保存帯入り口において、低RARでの操業時の還元粉化量を正しく求めるためには、500〜550℃の滞留時間を10分程度とする必要があり、従って、全てのRARについて、その還元粉化量を、一律の条件で正しく求めるためには、500〜550℃の滞留時間を10分以上とすることが望ましいことが分かった。また、最終到達する還元粉化量を求めることで、焼結鉱銘柄の還元粉化量の大小も評価することができる。 In other words, at the entrance of the blast furnace heat storage zone, it is necessary to set the residence time at 500 to 550 ° C to about 10 minutes in order to correctly determine the amount of reduced powder during operation at low RAR. In order to correctly obtain the reduced powdered amount under uniform conditions, it was found that the residence time at 500 to 550 ° C. is preferably 10 minutes or more. Moreover, the magnitude | size of the reduced powdering quantity of a sintered ore brand can also be evaluated by calculating | requiring the final reduction powdering quantity.
次に、500〜550℃の滞留時間を10分に固定し、到達還元温度について調査した。図10に、到達還元温度とRDI´の関係を示す。還元温度が高くなると共に還元は進行する。一方、還元粉化は、700℃までは温度の上昇と共に還元粉化も進行するが、700℃を超えると還元粉化は飽和することが分かった。
この結果より、低温還元粉化評価では、還元温度の上昇と共にガス組成が変化し、500〜550℃の滞留時間を10分とする条件下で還元される場合、到達還元温度700℃で還元粉化が終了することが分かった。
Next, the residence time of 500 to 550 ° C. was fixed to 10 minutes, and the ultimate reduction temperature was investigated. FIG. 10 shows the relationship between the ultimate reduction temperature and RDI ′. The reduction proceeds as the reduction temperature increases. On the other hand, it was found that reduced powdering proceeds with increasing temperature up to 700 ° C., but reduced powder is saturated when it exceeds 700 ° C.
From this result, in the low-temperature reduction powdering evaluation, when the gas composition changes as the reduction temperature rises and reduction is performed under the condition that the residence time of 500 to 550 ° C is 10 minutes, the reduced powder is reached at an ultimate reduction temperature of 700 ° C. It was found that the process ended.
また、図11に到達還元率とRDI´の関係を示す。到達還元率とRDI´も到達還元温度とRDI´の関係同様に、到達還元率６％のところで還元粉化の飽和現象が見られる。
従って、到達還元率を６％以上とすることで、高炉の熱保存帯入り口部における焼結鉱の還元粉化量を正しく判断できるものと考えられる。
以上のような知見を得て、本発明を完成させた。
FIG. 11 shows the relationship between the ultimate reduction rate and RDI ′. Similarly to the relationship between the ultimate reduction temperature and RDI ', the ultimate reduction rate and RDI' show a reduction phenomenon of reduction powder at an ultimate reduction rate of 6%.
Therefore, it is considered that the amount of reduced powdered sintered ore at the entrance of the heat preservation zone of the blast furnace can be correctly determined by setting the ultimate reduction rate to 6% or more.
Obtaining the above knowledge, the present invention has been completed.
すなわち、上記知見に基づく本発明の要旨構成は次のとおりである。
（１）鉱石系原料である焼結鉱の高炉内における低温還元粉化の評価方法において、該評価方法に用いる還元ガスとしてCO、CO2、およびN2からなる混合ガスを用い、上記COの配合量が10〜80vol％で、かつ上記COと上記CO2のガス比が0.4≦CO/(CO＋CO2)≦0.9の範囲を満たしつつ、該評価方法における還元試験時の温度変化に応じて、上記のガス比を変化させることを特徴とする焼結鉱の低温還元粉化評価方法。
That is, the gist configuration of the present invention based on the above knowledge is as follows.
(1) In a method for evaluating low-temperature reduced pulverization of sintered ore, which is an ore-based raw material, in a blast furnace, a mixed gas composed of CO, CO 2 and N 2 is used as a reducing gas used in the evaluation method, While the blending amount is 10 to 80 vol%, and the gas ratio of the CO and the CO 2 satisfies the range of 0.4 ≦ CO / (CO + CO 2 ) ≦ 0.9, according to the temperature change during the reduction test in the evaluation method, A method for evaluating low-temperature reduced pulverization of sintered ore, wherein the gas ratio is changed.
（２）前記還元試験において、還元試験時の温度上昇に応じて、ガス比CO/(CO＋CO2)を増大させることを特徴とする前記（１）に記載の焼結鉱の低温還元粉化評価方法。 (2) In the reduction test, the gas ratio CO / (CO + CO 2 ) is increased in accordance with the temperature rise during the reduction test, and the low-temperature reduced pulverization evaluation of the sintered ore according to (1) above Method.
（３）前記高炉内における低温還元粉化の評価位置が、熱保存帯入り口であることを特徴とする前記（１）または（２）に記載の焼結鉱の低温還元粉化評価方法。 (3) The evaluation method for low-temperature reduced pulverization of sintered ore according to (1) or (2) above, wherein the evaluation position of low-temperature reduced pulverization in the blast furnace is a heat preservation zone entrance.
（４）前記（１）〜（３）のいずれかに記載の還元試験において、焼結鉱の到達還元温度を少なくとも700℃とし、かつ500〜550℃の範囲に10分以上保持することを特徴とする焼結鉱の低温還元粉化評価方法。 (4) In the reduction test according to any one of (1) to (3), the ultimate reduction temperature of the sintered ore is at least 700 ° C. and is maintained in the range of 500 to 550 ° C. for 10 minutes or more. A method for evaluating low-temperature reduced powdering of sintered ore.
（５）前記（１）〜（４）のいずれかに記載の還元試験において、焼結鉱の到達還元率を少なくとも６％とすることを特徴とする焼結鉱の低温還元粉化評価方法。 (5) In the reduction test according to any one of (1) to (4), a low-temperature reduced pulverization evaluation method for sintered ore, wherein the ultimate reduction rate of the sintered ore is at least 6%.
本発明は、焼結鉱の低温還元粉化現象が終了するまで還元を行うため、実製造の高炉内の熱保存帯入口部における焼結鉱の低温還元粉化現象により生じる最終粉化量を、安定して、より正確に評価することができる。また、最終粉化量から焼結銘柄の品位差を検出することができる。さらに、焼結銘柄の如何にかかわらず共通の還元試験条件で済むので、評価作業の簡便化を図ることができる。 Since the present invention performs reduction until the low-temperature reduced pulverization phenomenon of the sintered ore is completed, the final pulverization amount generated by the low-temperature reduced pulverization phenomenon of the sintered ore at the entrance of the heat preservation zone in the actual blast furnace is reduced It can be evaluated stably and more accurately. Further, the quality difference of the sintered brand can be detected from the final powdered amount. Furthermore, since the common reduction test conditions are sufficient regardless of the sintered brand, the evaluation work can be simplified.
以下、本発明を具体的に説明する。
本発明は、JIS M 8720に示された低温還元粉化試験に準ずるものであるが、特に還元雰囲気を、COとN2からCO、CO2、およびN2の混合ガスに変更し、このガス比〔CO/(CO＋CO2)〕を還元温度に応じて変化させることが本発明の最も重要なところである。
The present invention will be specifically described below.
The present invention is intended to conform to the low temperature reduction degradation test shown in JIS M 8720, in particular the reducing atmosphere changed from CO and N 2 CO, CO 2, and the mixed gas of N 2, this gas It is the most important aspect of the present invention that the ratio [CO / (CO + CO 2 )] is changed according to the reduction temperature.
上記した混合ガス成分の内、基本成分であるCOの配合量は10〜80vol％とする。COが10vol％未満の場合は、混合ガスの還元力が小さく、試験時間が長時間となるからである。一方、80vol％を超えると、還元粉化の終了する還元率が高くなりすぎ、本発明の効果が薄れるからである。なお、COの範囲は好ましくは、20〜50vol％である。 Among the mixed gas components described above, the blending amount of CO, which is a basic component, is 10 to 80 vol%. This is because when the CO content is less than 10 vol%, the reducing power of the mixed gas is small and the test time is long. On the other hand, when it exceeds 80 vol%, the reduction rate at which the reduction powdering is completed becomes too high, and the effect of the present invention is diminished. The CO range is preferably 20 to 50 vol%.
次に、COとCO2について考える。COは、CO2と酸素を介して平衡状態を作る。従って、上記した３元系の混合ガス中の還元能力は、CO/(CO＋CO2)に関係することが分かる。
そこで、本発明のCO/(CO＋CO2)をパラメータとし、以下の試験条件で低温還元粉化試験を実施した。
Next, consider CO and CO 2 . CO creates an equilibrium through CO 2 and oxygen. Therefore, the reduction capability of a mixed gas of ternary systems described above, it is seen that related to CO / (CO + CO 2) .
Therefore, a low-temperature reduction powdering test was performed under the following test conditions using CO / (CO + CO 2 ) of the present invention as a parameter.
本試験に用いる還元試験装置は、従来公知のJIS-RDI試験装置で良く、焼結鉱試料は、A：高RDI焼結鉱、B：中RDI焼結鉱、C：低 RDI焼結鉱、粒径：16〜20mm、重量：500ｇ（＝Ｗinitial）の３種類を用いた。また、還元条件は、高炉の炉頂のガス組成を参考にN2：55vol％一定として、CO、CO2の値を種々に変化させ、また、還元温度は550℃、還元時間は30分とした。この時、CO/(CO＋CO2)の値は、0.3〜1.0の範囲で0.1刻みで行った。ついでJIS M 8720に準拠した条件でドラムテストを行い、-2.8mmの粉率を求めた。試験結果を表1に示す。 The reduction test equipment used in this test may be a conventionally known JIS-RDI test equipment, and the sintered ore samples are A: high RDI sintered ore, B: medium RDI sintered ore, C: low RDI sintered ore, Three types having a particle size of 16 to 20 mm and a weight of 500 g (= W initial ) were used. The reduction conditions are as follows: N 2 : 55 vol% is constant with reference to the gas composition at the top of the blast furnace, the values of CO and CO 2 are varied, the reduction temperature is 550 ° C, and the reduction time is 30 minutes. did. At this time, the value of CO / (CO + CO 2 ) was in the range of 0.3 to 1.0 in increments of 0.1. Next, a drum test was performed under the conditions in accordance with JIS M 8720 to obtain a powder ratio of -2.8 mm. The test results are shown in Table 1.
同表に示した結果から、RDI値と実際の試料（RDI´）値とでは、値に差が有り、粉末の焼結鉱種の差による補正をしないと、実製造には使えないことが分かる。
さらに、CO/(CO＋CO2)の値が0.4〜0.9の範囲であればRDI´値は、ガス組成によらず、ほぼ一定となっていることが分かる。また、CO/(CO＋CO2)の値が0.5〜0.8の場合には、ばらつきがさらに小さいことが分かる。
以上の結果より、本発明のCO/(CO＋CO2)の値は0.4〜0.9とした。より好ましい範囲は0.5〜0.8である。
From the results shown in the table, there is a difference between the RDI value and the actual sample (RDI´) value, and it cannot be used in actual production unless it is corrected by the difference in the sintered ore type of the powder. I understand.
Furthermore, it can be seen that if the value of CO / (CO + CO 2 ) is in the range of 0.4 to 0.9, the RDI ′ value is substantially constant regardless of the gas composition. Further, if the value of CO / (CO + CO 2) is 0.5 to 0.8, the variation can be seen smaller.
From the above results, the value of CO / (CO + CO 2 ) of the present invention was set to 0.4 to 0.9. A more preferable range is 0.5 to 0.8.
本発明では、CO/(CO＋CO2)の値を、還元温度の変化に応じて変化させている。その設定の基本は、高炉条件の模擬である。以下に具体的な温度変化手順を説明する。
本発明での温度の変化は、連続的でも段階的でもよいが、３〜５段階程度に上昇させることが、試験温度を安定化させる面から好適である。そこで、以下、３段階の温度領域に設定した場合について説明する。
最初の温度領域の開始温度は、200℃程度が好ましい、というのは、200℃未満は還元反応がほとんど起こらない領域だからである。ついで、最初の温度領域の終点は、550℃を超えた600〜800℃程度とするのがよい（これを第１ステップとする）。
次に、この終点を開始温度として、700〜900℃程度までを次領域とするのがよい（これを第２ステップとする）。最後の領域は、この終点を開始温度として最終到達温度までとするのがよい（これを第３ステップとする）。
このように、還元温度を段階的に変化させることにより、高炉の実操業に即したRDI´値を把握することができる。
なお、各々のCO/(CO＋CO2)の値は、第１ステップが0.4〜0.6程度、第２ステップが0.6〜0.7程度、第３ステップが0.7〜0.9程度とするのが好適である。
In the present invention, the value of CO / (CO + CO 2 ) is changed according to the change in the reduction temperature. The basis of the setting is simulation of blast furnace conditions. A specific temperature change procedure will be described below.
Although the temperature change in the present invention may be continuous or stepwise, it is preferable to increase the temperature to about 3 to 5 from the viewpoint of stabilizing the test temperature. Therefore, the case where the temperature range is set in three stages will be described below.
The starting temperature of the first temperature region is preferably about 200 ° C., because the temperature below 200 ° C. is a region in which the reduction reaction hardly occurs. Next, the end point of the first temperature region is preferably about 600 to 800 ° C. exceeding 550 ° C. (this is the first step).
Next, this end point is set as a starting temperature, and the next region is preferably set to about 700 to 900 ° C. (this is a second step). In the last region, this end point should be set as the start temperature to the final temperature reached (this is the third step).
Thus, by changing the reduction temperature stepwise, it is possible to grasp the RDI ′ value in accordance with the actual operation of the blast furnace.
The values of CO / (CO + CO 2 ) are preferably about 0.4 to 0.6 for the first step, about 0.6 to 0.7 for the second step, and about 0.7 to 0.9 for the third step.
本発明では、高炉内熱保存帯入り口の還元粉化量を求めるために、その還元粉化量を飽和させる必要があり、前述したとおり、この到達還元率は６％以上が望ましい。
到達還元率に到達する手段としては、焼結鋼中のT.FeとFeOの比が予め分かっているものはその値を使用すれば良く、分かっていない場合には、JIS M 8212「鉄鉱石−全鉄定量方法」：2005年、JIS M 8213「鉄鉱石−酸可溶性鉄 (II) 定量方法」：1995年等によって、焼結鋼中のT.FeとFeOの割合を測定し、還元率６％に到達する重量減少量（Ｗ6）を計算すれば良い。ついで、還元試験装置に、熱天秤等の試料重量測定器を設置する。還元試験中の焼結鉱重量がＷinitial−Ｗ6となったところで、還元試験を終了すれば、安定して目標還元率６％を得ることができ、従来法で見られた還元不足による再試験を行う必要はなくなる。
In the present invention, it is necessary to saturate the reduced powdered amount in order to obtain the reduced powdered amount at the entrance of the blast furnace heat preservation zone, and as described above, the ultimate reduction rate is desirably 6% or more.
As a means to reach the ultimate reduction rate, if the ratio of T.Fe and FeO in the sintered steel is known in advance, it is sufficient to use that value. If it is not known, JIS M 8212 “Iron Ore -Total iron determination method ": 2005, JIS M 8213" Iron ore-acid-soluble iron (II) determination method ": 1995. The ratio of T.Fe and FeO in sintered steel was measured, and the reduction rate What is necessary is just to calculate the weight reduction amount (W 6 ) reaching 6%. Next, a sample weight measuring instrument such as a thermobalance is installed in the reduction test apparatus. When the weight of the sintered ore during the reduction test reaches W initial −W 6 , if the reduction test is finished, the target reduction rate of 6% can be stably obtained. There is no need to conduct a test.
本発明の還元温度の条件は、到達還元温度を少なくとも700℃、かつ500〜550℃の範囲を10分以上保持することが望ましい。前述したとおり、700℃に満たないと前記した還元粉化量に達しないおそれが出てくる。また、500〜550℃の範囲を10分以上保持しないと低RARでの操業時の還元粉化量が正しく評価できない。
また、還元時間については、特に制限はないが、上記の保持時間を含めて60分程度で十分である。
As for the conditions of the reduction temperature of the present invention, it is desirable to keep the ultimate reduction temperature at least 700 ° C. and the range of 500 to 550 ° C. for 10 minutes or more. As described above, there is a risk that the reduced powdered amount will not be reached unless the temperature is lower than 700 ° C. Moreover, if the range of 500-550 degreeC is not hold | maintained for 10 minutes or more, the amount of reduced powdering at the time of a low RAR operation cannot be evaluated correctly.
The reduction time is not particularly limited, but about 60 minutes including the above holding time is sufficient.
従来の評価指標であるJIS-RDI値および本発明により求めたRDI´値と、高炉内の各位置における圧損との関係を図12に示す。
図中(5)、(6)、(7)は、圧損を測定した位置であり、実際は、羽口からそれぞれ、17.68ｍ、19.54ｍ、21.08ｍの距離にある。また圧損は、高炉に標準設置されているシャフト圧力計を用いて測定を行った。
FIG. 12 shows the relationship between the JIS-RDI value, which is a conventional evaluation index, the RDI ′ value obtained by the present invention, and the pressure loss at each position in the blast furnace.
In the figure, (5), (6), and (7) are the positions at which the pressure loss was measured, and are actually at the distances of 17.68 m, 19.54 m, and 21.08 m from the tuyere, respectively. The pressure loss was measured using a shaft pressure gauge installed as standard in the blast furnace.
これらの試験に供した試料は、複数の実製造の焼結鉱を使用し、RDIは、JIS M 8720に従い、RDI´は、図７中の条件を使用し、特にCO/(CO+CO2)の値を、200〜800℃では0.5に、800〜900℃では0.6に、および900〜1000℃では0.72に変化させる条件で行った。また、高炉の主な操業条件は表２に示す。 Samples used in these tests use a plurality of actual manufactured ores, RDI conforms to JIS M 8720, RDI ′ uses the conditions shown in FIG. 7, and particularly CO / (CO + CO 2 ) Was changed to 0.5 at 200-800 ° C, 0.6 at 800-900 ° C, and 0.72 at 900-1000 ° C. Table 2 shows the main operating conditions of the blast furnace.
図12に示したとおり、JIS-RDI試験で求めた還元粉化量と高炉内圧損の関係については、低JIS-RDI値側で還元粉化量と高炉内圧損の関係が一定となり、還元粉化量が高炉内通気性に及ぼす影響が明確に反映されていないことが分かる。
これに対し、本発明により得られたRDI´値は、高炉内のいずれの場所においても明確な相関が得られている。
また、還元粉化した焼結鉱粉がシャフト部の通気に及ぼす影響は下部ほど大きくなるため、シャフト下部における粉化量の推定はたいへん重要であるが、本発明により、シャフト下部、つまり高炉内熱保存帯入り口における還元粉化量を、高炉内環境を模擬し、正確に評価できることが可能となった。
As shown in Fig. 12, regarding the relationship between the reduced powdering amount obtained in the JIS-RDI test and the pressure loss in the blast furnace, the relationship between the reduced powdering amount and the pressure loss in the blast furnace is constant on the low JIS-RDI value side. It can be seen that the effect of the conversion amount on the blast furnace air permeability is not clearly reflected.
On the other hand, the RDI ′ value obtained by the present invention has a clear correlation at any location in the blast furnace.
In addition, since the effect of reduced powdered sintered ore on the ventilation of the shaft portion becomes larger in the lower part, it is very important to estimate the amount of powder in the lower part of the shaft. It has become possible to accurately evaluate the amount of reduced powder at the entrance of the heat preservation zone by simulating the blast furnace environment.
本発明は、高炉内熱保存帯入り口における焼結鉱の還元粉化量についても、高炉内環境を模擬し、正確に評価できるため、本評価方法を高炉操業時の還元粉化量管理として適用することで、安定した高炉操業、ひいては、安定した焼結鉱の品質を確保することができる。 Since the present invention simulates the environment in the blast furnace and can accurately evaluate the reduced pulverization amount of the sintered ore at the entrance of the blast furnace thermal preservation zone, this evaluation method is applied as the reduced pulverization amount management during blast furnace operation. By doing so, it is possible to ensure stable blast furnace operation, and thus stable sinter quality.
１ はかり
２ エアシリンダ
３ ロードセル
４ 排気ガス分析
５ 熱電対
６ 試料
７ アルミナボール
８ 電気ヒータ
1 Scale 2 Air Cylinder 3 Load Cell 4 Exhaust Gas Analysis 5 Thermocouple 6 Sample 7 Alumina Ball 8 Electric Heater
Claims (5)
The reduction test according to any one of claims 1 to 4, wherein the ultimate reduction rate of the sintered ore is at least 6%.
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| KR101368562B1 (en) | 2012-06-28 | 2014-02-28 | 현대제철 주식회사 | Ri calculating method for using rdi in blast furnace |
| KR101443448B1 (en) | 2012-07-30 | 2014-09-19 | 현대제철 주식회사 | Prediction method for sinter ore with rdi |
| CN114354676A (en) * | 2022-01-11 | 2022-04-15 | 内蒙古科技大学 | Method and device for detecting reduction and expansion performance of pellet |
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| JP2003301224A (en) * | 2002-04-12 | 2003-10-24 | Nippon Steel Corp | Test method for strength of sintered ore after reduction |
| JP2006249507A (en) * | 2005-03-10 | 2006-09-21 | Nippon Steel Corp | Method for evaluating reducibility of sintered ore |
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| JP2003301224A (en) * | 2002-04-12 | 2003-10-24 | Nippon Steel Corp | Test method for strength of sintered ore after reduction |
| JP2006249507A (en) * | 2005-03-10 | 2006-09-21 | Nippon Steel Corp | Method for evaluating reducibility of sintered ore |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101368562B1 (en) | 2012-06-28 | 2014-02-28 | 현대제철 주식회사 | Ri calculating method for using rdi in blast furnace |
| KR101443448B1 (en) | 2012-07-30 | 2014-09-19 | 현대제철 주식회사 | Prediction method for sinter ore with rdi |
| CN114354676A (en) * | 2022-01-11 | 2022-04-15 | 内蒙古科技大学 | Method and device for detecting reduction and expansion performance of pellet |
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